Rotary jar



Nov. 9, 1937. w. L. FOSTER Er AL 2,098,491

ROTARY JAR Filed July 6, 1956 2 Sheets-Sheet` l Nv. 9, 1937. w. L. FOSTER ET Al. 2,098,491

ROTARY JAR Filed July` 6, 1936 2 sheets-sheet 2 Patented Nov. 9, 1937 UNITED STATES PATENT OFFICE ROTARY JAR Application July 6, 1936, Serial No. 88,916

3 Claims.

This invention deals with jars used in well drilling for loosening bits, pipe or other objects that have become lodged in the well, and which comprise a telescopic body and mandrel restrained against relative longitudinal movement by interengaging clutch jaws which are releasable when subjected to a predetermined pull or stretch, after which striking shoulders on the body and mandrel come into impacting engagement with the resultant blow or jar being transmitted to the lodged object.

Generally speaking, the present jar is of the type in which a straight upward pull releases the clutch members to permit relative longitudinal movement of the body and mandrel, and straight downward movement resets the clutch members. Although relative rotation of the body and mandrel occurs during release and resetting of the clutch members, it is only necessary to impart a straight upward pull or 'downward movement to the drill string. Release of the clutch members is effected by disposing the bearing faces of the clutch jaws at such an angle of slip that will allow the jaws to remain in full engagement until a predetermined pull is imparted to the drill string and to the clutch jaws, whereupon said jaws will slip from engagement and cause the mandrel to rotate relative to the body.

It is desirable that the drill string be free from torsional strain when the upward pull is imparted so that when krelative rotation of the body and the mandrel occurs, thelower end of the drill string above the jar will be free to rotate and thus transmit little or no rotative force to the shing tool. Thus the invention differsfrom other jars of similar construction in that no rotational forces are transmitted to the fishing tool which might have a tendency to free it from the sh,

The main object of this invention is to provide a jar wherein the clutch members may be released and reengaged by straight upward and downward Vmovement and without the applicationrof rotational forces. Other objects are to provide a jar Ywherein certain of-n its moving parts cannot become `jammed by .bit cuttings or other foreign matter. Also `.to provide a jar that is rugged, simple in construction, short, and easy to operate. Y

A description of certain forms of the inven- `tionwill Ybest serve to illustrate and further eX- plain the above mentioned features as well vas additional objectsfanddetails of the invention, without the necessity for further preliminary (Cl. Z55-27) remarks. Such typical forms are treated in the following description, throughout which reference is had to the accompanying drawings, in which:

Fig. r1 is a longitudinal sectional view, partly in elevation, showing the jar in the collapsed or drilling position;

Fig. 2 is a View similar to Fig. 1 but showing the jar in the fully extended or jarring position;

Fig. 3 is an enlargement of a portion of that shown in Fig. 1;

Figs. 4 and 5 are sections on` lines '4-4 and 5-5 of Figs. l and 3, respectively;

Fig. 6 is a developed view showing the relative positions of the clutch jaws at different stages of operation; and

Fig. 'l is a fragmentary view showing a modi- :ed form of jar eliminating certain of the parts shown in Fig. 1.

Referring to Figs. 1 to 5, the operating'or drill string Ill is connected at its lower end to the mandrel, generally'indicated at II, by coupling I2 threadedly connected at I3 to the lower end of the drill stringiand at I4 to the upper end of the mandrel. The lower end of the mandrel is telescopically taken within bore I I of the body generally indicated at I8. Body I8 is connected at its lower endto a lower section of the pipe string 29 by coupling 2l threadedeat 22 into the lower end of the body and connected at 23 to the upper end ofthe pipe string 20, the latter carrying at its lower end a drill bit, fishing tool or the like (not shown). i

Body I8 has threaded into its upper end a bushing 25, the latter having a bore 26 which has a sliding t within the mandrel II. .Below bushing 25, the body has an enlarged bore 28 which receives la rotatable sleeve 29, vshoulder 30 at the lower end of .bore 28 actingin conjunction with the lower end 3I ofl the vbushingZti to longitudinally confine the sleeve. Assshown in Figs. 3 and 5, sleeve 29 is externallyreduced as indicated at to provide space for a torsion .spring 38. One end 3l of spring 3B is received by a recess 38 in thesleeve andthe other end 39 is received by a recess 40 in bushing 25. Bore 43 of sleeve 29 slidably engages mandrel Il and rotative connection ,therebetween is provided by keys 44 which are attached to sleeve 29 as by welding and received by ways 45 running longitudinally of the mandrel.

Mandrel II carries at its lower end an enlarged head 4l and shoulder 48 thereof is adapted to .come into striking engagement with the `lower end 49 of the vsleeve upon relative `longitudinal extending movement of the mandrel and the body. A wash hole extends through mandrel and coupling l2. Threaded into the lower end of the mandrel is a wash tube 5| which passes through bore 52 and packing gland 53 in coupling 2| and which is of sufficient length to remain packed 01T by gland 53 throughout the relative longitudinal travel of the body and mandrel.

A Vplurality of circularly spaced clutch members (here shown as two in number) are mounted on the body andrextend longitudinally from one end thereof. For simplicity of construction, the members 60 are formed integrally with a bushing 25'and extend upwardly therefrom. A plurality of circularly spaced members 6| (equal in number to members 60) are mounted on the mandrel and, for simplicity of construction, are formed integrally with and longitudinally depend from coupling I2. After the mandrel is threaded into coupling I2, members 6I may be additionally strengthened by welding them to the mandrel as indicated at 6|a. As illustrated, circularly spaced pairs of members 60 and 6| are so arranged that one pair is received by the spaces between the members of the other pair and remain so related throughout the relative longitudinal travel of the body and the mandrel to provide rotative driving connection between the body and mandrel. Members 60 and 6| will hereinafter be referred to as body members 60 and mandrel members 6|, respectively.

Formed on one side of each of the body members BIJ is a pair of longitudinally spaced clutch jaws 62 and 65, the upper jaws each having an inclined and downwardly disposed bearing face 63 and the lower jaws each having an inclined and downwardly disposed bearing face 64. Mandrel members 6| are similar in some respects to body members 60. Formed on one side of each of the mandrel members 6| is a pair of longitudinally spaced clutch jaws 66 and 68, the upper laws each having an inclined and upwardly disposed bearing face 61 and the lower jaws each having an inclined and upwardly disposed bearing face 69. Jaws 66 and 68 are adapted to engage jaws 62 and 65, respectively, by limited lrelative rotation of the mandrel and the body in one direction, and to disengage by limited relative rotation of the mandrel and body in the opposite direction, Relative rotation of the body and the mandrel in the direction of jaw engage-r ment is, in one manner, accomplished by the camming action of cam surfaces 13 and 14 formed on mandrel members 6| and body member 60, respectively, when said cam surfaces are brought into engagement by downward movement of the mandrel relative to the body. When the mandrel reaches itsl limit of downward movement, jaws 66 and 6B will have been rotated into longitudinal alignment with jaws 62 and 65, respectively,

4 which position is indicated in Fig. l.

Relative rotation of the body and mandrel in the direction of jaw disengagement occurs when a predetermined upward pull is imparted to the mandrel. This rotation is accomplished by inclining the bearing faces of the jaws at such an angle of slip whereby the jaws will remain in full engagement until the predetermined pull is imparted and will then slip from engagement.

During relative rotation of the body and mandrel, when the jaws slip from engagement, a torsional stress is imparted to spring 36, end 31 of the spring rotating with the mandrel and end 39 being held within recess 4l) of. the bOdy.

Spring 36, when so stressed, tends to rotate the mandrel relative to the body in a direction of J'aw engagement and when the mandrel is moved downwardly with respect to the body, it assists cams 13 and 14 in accomplishing reengagement of the jaws. If a spring of sufcient strength is used, it may be relied upon to accomplish reengagement of the jaws without the use of cams 13 Vand 14. However, since such a spring would tend to prevent instantaneous disengagement of the jaws, it is desirable to use a lighter spring in conjunction with the cams to accomplish said reengagement, Moreover, as will later appear, spring 36 and sleeve 29 may be dispensed with in Which case reengagement of the jaws is accomplished entirely by cams 13 and 14,

Although if desired, the body and mandrel clutch members 60 and 6| may be enclosed, it is preferable to have them outwardly exposed to the well fluid. Since these members are exposed, they are continually being washed by the well fluid and, by the same token, as they move together, any particles wedged therebetween are free to be squeezed outwardly. The area of the contacting surfaces of members 6U and 6| may be minimized by relieving or cutting away portions of one of said members as indicated at 11.

In operation, the jar is lowered into the well bore in the extended position indicated in Fig. 2, the jar being attached to the lower end of the drill string and a bit, fishing tool or the like depending from the jar. After the bit or shing tool comes to rest at the bottom of the well or upon the lodged object, as the case may be, further downward movement of the drill string causes the mandrel to move downwardly with respect to the body. As the mandrel nears its limit of downward movement relative to the body, cam surface 13 contacts cam surface 14 as indicated in dotted lines in Fig. 6. Upon further downward movement of the mandrel, bearing faces 61 and 69 are rotated into longitudinal alignment with bearing faces 63 and 64', respectively, both by the action of cam surfaces 13 and 14, and by the action of torsion spring 36. While the jar is in this position, the operator frees the drill string for rotative movement so that the drill string may unwind and free itself from any torsional strains which might have been imposed. The drill string and the mandrel are then raised until the bearing faces 61 and 69 come into contact with bearing faces 63 and 64, respectively, which contact arrests further upward movement of the mandrel. An upward pull or stretch is then increasingly imposed upon the drill string until the load becomes suflicient to cause the jaws 66 and 68 to rotatively slip out of engagement with jaws 62 and 65, respectively. Rotative movement 0f the mandrel relative to the body during the disengaging movement of the jaws imposes a torsional load in spring 36. This spring, however, is light and its purpose is to assist in reengagement of the jaws and not necessarily to control the disengagement of said jaws.

Since the drill string is free from torsional strain, it offers practically no resistance to this slight amount of rotation and therefore practically vno rotative force is transmitted to the tool. Upon disengagement of the jaws, the tension in the drill string causes the mandrel to move upwardly, jaws 68 riding on the longitudinal faces of members 60, until shoulder 48 on the mandrel impacts against shoulder 48 of sleeve 29, the blow being transmitted through the body to the tool below. If a second blow Cil or jar is required, the tool is reset by lowering the drill string. The mandrel is moved downwardly with respect to the body until cam surface 'i3 contacts cam surface 14 as shown in dotted lines in Fig. 6. If the frictional resistance between the body and the mandrel is not too great, spring 355, being under strain, will return the jaws into longitudinal alignment. However, upon further downward movement of the mandrel cam surfaces i3-14 will, with the assistance of sp-ring 36, rotate the jaws into longitudinal alignment to the full line position of Fig. 6.

The variational form of the invention shown in Fig. 7, while being generally similar to the described embodiment, differs with respect to the means of jaw reengagement in that spring 36 and sleeve 29 are omitted. Other parts of the two forms are similar and have been given corresponding numerals. In this form, the reengagement of the jaws is accomplished by the camming action of cam surfaces 13 and 14. Sleeve 29 being omitted, bushing 25 becomes the anvil and shoulder 3la thereof is engaged by shoulder 48 to impact the jarring blow to the body and the tool.

It is to be understood that the present jar will operate equally as well in the inverted position and any statements regarding direction of movement or disposition of parts are to be construed accordingly.

We claim:

1. In a jar, a body, a mandrel limitedly longitudinally movable and limitedly rotatable in said body, striking shoulders on the mandrel and body and which are brought into engagement by relative longitudinal movement of the mandrel in one direction, said body and mandrel having interengaging transverse shoulders and a longitudinal bearing surface, which shoulders are adapted to be moved out of interengagement by relative rotation of the body and mandrel in one direction, to allow relative longitudinal movement in the stated direction, and which longitudinal bearing surface maintains contact between the body and mandrel during such longitudinal movement, a spring tending torelatively rotate the body and mandrel opposite to the direction which causes shoulder disengagement, and interengaging cam faces on the body and mandrel acting positively to rotate the body and mandrel relatively in said last mentioned direction by virtue of their relative longitudinal movement in the direction opposite to that first stated.

2. In a jar, a body, a mandrel arranged for limited relative longitudinal movement in said body, striking shoulders which are brought into engagement by relative longitudinal movement of the body and the mandrel in one direction, a plurality of circularly spaced members mounted on and extending longitudinally from one end of the body, a plurality of circularly spaced members on the mandrel, said members extending from the body being received within spaces between said members on the mandrel, a plurality of clutch jaws formed on one side of each of said members, said jaws being adapted to engage one with another to restrain relative longitudinal movement of the body and mandrel in said direction until a predetermined pull is exerted,

whereupon said jaws will slip causing said body and mandrel to relatively rotate until free for relative longitudinal movement in said direction, and means cooperating with said members to return said jaws into reengagement, said means comprising cam surfaces on the body and mandrel respectively which are brought into engagement upon relative longitudinal movement of said body and mandrel in the opposite direction. 3. In a jar adapted to be lowered in a well, a body and a mandrel arranged for limited rela tive longitudinal movement, striking shoulders which are brought into engagement by relative longitudinal movement of the body and the mandrel in onedirection, a plurality of jaws openly exposed to the well fluid and connected with the body and the mandrel respectively, said jaws being adapted to engage to restrain said body and mandrel against relative longitudinal movement in said direction until a predetermined pull is exerted, whereupon said jaws will slip from engagement, and means for reengaging said jaws upon relative longitudinal movement of the body and mandrel in the opposite direction, said means comprising cams on the body and mandrel adapted to cause said mandrel to rotate relative to said body.

WALTER L. FOSTER. JAMES J. SANTIAGO. 

